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Diffstat (limited to 'contrib/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp')
| -rw-r--r-- | contrib/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp | 2593 |
1 files changed, 2593 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/contrib/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp new file mode 100644 index 0000000..dc07440 --- /dev/null +++ b/contrib/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp @@ -0,0 +1,2593 @@ +//===------ SimplifyLibCalls.cpp - Library calls simplifier ---------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This is a utility pass used for testing the InstructionSimplify analysis. +// The analysis is applied to every instruction, and if it simplifies then the +// instruction is replaced by the simplification. If you are looking for a pass +// that performs serious instruction folding, use the instcombine pass instead. +// +//===----------------------------------------------------------------------===// + +#include "llvm/Transforms/Utils/SimplifyLibCalls.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/StringMap.h" +#include "llvm/ADT/Triple.h" +#include "llvm/Analysis/TargetLibraryInfo.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/DiagnosticInfo.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/Support/Allocator.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Transforms/Utils/BuildLibCalls.h" +#include "llvm/Transforms/Utils/Local.h" + +using namespace llvm; +using namespace PatternMatch; + +static cl::opt<bool> + ColdErrorCalls("error-reporting-is-cold", cl::init(true), cl::Hidden, + cl::desc("Treat error-reporting calls as cold")); + +static cl::opt<bool> + EnableUnsafeFPShrink("enable-double-float-shrink", cl::Hidden, + cl::init(false), + cl::desc("Enable unsafe double to float " + "shrinking for math lib calls")); + + +//===----------------------------------------------------------------------===// +// Helper Functions +//===----------------------------------------------------------------------===// + +static bool ignoreCallingConv(LibFunc::Func Func) { + return Func == LibFunc::abs || Func == LibFunc::labs || + Func == LibFunc::llabs || Func == LibFunc::strlen; +} + +/// Return true if it only matters that the value is equal or not-equal to zero. +static bool isOnlyUsedInZeroEqualityComparison(Value *V) { + for (User *U : V->users()) { + if (ICmpInst *IC = dyn_cast<ICmpInst>(U)) + if (IC->isEquality()) + if (Constant *C = dyn_cast<Constant>(IC->getOperand(1))) + if (C->isNullValue()) + continue; + // Unknown instruction. + return false; + } + return true; +} + +/// Return true if it is only used in equality comparisons with With. +static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) { + for (User *U : V->users()) { + if (ICmpInst *IC = dyn_cast<ICmpInst>(U)) + if (IC->isEquality() && IC->getOperand(1) == With) + continue; + // Unknown instruction. + return false; + } + return true; +} + +static bool callHasFloatingPointArgument(const CallInst *CI) { + return std::any_of(CI->op_begin(), CI->op_end(), [](const Use &OI) { + return OI->getType()->isFloatingPointTy(); + }); +} + +/// \brief Check whether the overloaded unary floating point function +/// corresponding to \a Ty is available. +static bool hasUnaryFloatFn(const TargetLibraryInfo *TLI, Type *Ty, + LibFunc::Func DoubleFn, LibFunc::Func FloatFn, + LibFunc::Func LongDoubleFn) { + switch (Ty->getTypeID()) { + case Type::FloatTyID: + return TLI->has(FloatFn); + case Type::DoubleTyID: + return TLI->has(DoubleFn); + default: + return TLI->has(LongDoubleFn); + } +} + +/// \brief Check whether we can use unsafe floating point math for +/// the function passed as input. +static bool canUseUnsafeFPMath(Function *F) { + + // FIXME: For finer-grain optimization, we need intrinsics to have the same + // fast-math flag decorations that are applied to FP instructions. For now, + // we have to rely on the function-level unsafe-fp-math attribute to do this + // optimization because there's no other way to express that the call can be + // relaxed. + if (F->hasFnAttribute("unsafe-fp-math")) { + Attribute Attr = F->getFnAttribute("unsafe-fp-math"); + if (Attr.getValueAsString() == "true") + return true; + } + return false; +} + +/// \brief Returns whether \p F matches the signature expected for the +/// string/memory copying library function \p Func. +/// Acceptable functions are st[rp][n]?cpy, memove, memcpy, and memset. +/// Their fortified (_chk) counterparts are also accepted. +static bool checkStringCopyLibFuncSignature(Function *F, LibFunc::Func Func) { + const DataLayout &DL = F->getParent()->getDataLayout(); + FunctionType *FT = F->getFunctionType(); + LLVMContext &Context = F->getContext(); + Type *PCharTy = Type::getInt8PtrTy(Context); + Type *SizeTTy = DL.getIntPtrType(Context); + unsigned NumParams = FT->getNumParams(); + + // All string libfuncs return the same type as the first parameter. + if (FT->getReturnType() != FT->getParamType(0)) + return false; + + switch (Func) { + default: + llvm_unreachable("Can't check signature for non-string-copy libfunc."); + case LibFunc::stpncpy_chk: + case LibFunc::strncpy_chk: + --NumParams; // fallthrough + case LibFunc::stpncpy: + case LibFunc::strncpy: { + if (NumParams != 3 || FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != PCharTy || !FT->getParamType(2)->isIntegerTy()) + return false; + break; + } + case LibFunc::strcpy_chk: + case LibFunc::stpcpy_chk: + --NumParams; // fallthrough + case LibFunc::stpcpy: + case LibFunc::strcpy: { + if (NumParams != 2 || FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != PCharTy) + return false; + break; + } + case LibFunc::memmove_chk: + case LibFunc::memcpy_chk: + --NumParams; // fallthrough + case LibFunc::memmove: + case LibFunc::memcpy: { + if (NumParams != 3 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || FT->getParamType(2) != SizeTTy) + return false; + break; + } + case LibFunc::memset_chk: + --NumParams; // fallthrough + case LibFunc::memset: { + if (NumParams != 3 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isIntegerTy() || FT->getParamType(2) != SizeTTy) + return false; + break; + } + } + // If this is a fortified libcall, the last parameter is a size_t. + if (NumParams == FT->getNumParams() - 1) + return FT->getParamType(FT->getNumParams() - 1) == SizeTTy; + return true; +} + +//===----------------------------------------------------------------------===// +// String and Memory Library Call Optimizations +//===----------------------------------------------------------------------===// + +Value *LibCallSimplifier::optimizeStrCat(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strcat" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2|| + FT->getReturnType() != B.getInt8PtrTy() || + FT->getParamType(0) != FT->getReturnType() || + FT->getParamType(1) != FT->getReturnType()) + return nullptr; + + // Extract some information from the instruction + Value *Dst = CI->getArgOperand(0); + Value *Src = CI->getArgOperand(1); + + // See if we can get the length of the input string. + uint64_t Len = GetStringLength(Src); + if (Len == 0) + return nullptr; + --Len; // Unbias length. + + // Handle the simple, do-nothing case: strcat(x, "") -> x + if (Len == 0) + return Dst; + + return emitStrLenMemCpy(Src, Dst, Len, B); +} + +Value *LibCallSimplifier::emitStrLenMemCpy(Value *Src, Value *Dst, uint64_t Len, + IRBuilder<> &B) { + // We need to find the end of the destination string. That's where the + // memory is to be moved to. We just generate a call to strlen. + Value *DstLen = EmitStrLen(Dst, B, DL, TLI); + if (!DstLen) + return nullptr; + + // Now that we have the destination's length, we must index into the + // destination's pointer to get the actual memcpy destination (end of + // the string .. we're concatenating). + Value *CpyDst = B.CreateGEP(B.getInt8Ty(), Dst, DstLen, "endptr"); + + // We have enough information to now generate the memcpy call to do the + // concatenation for us. Make a memcpy to copy the nul byte with align = 1. + B.CreateMemCpy(CpyDst, Src, + ConstantInt::get(DL.getIntPtrType(Src->getContext()), Len + 1), + 1); + return Dst; +} + +Value *LibCallSimplifier::optimizeStrNCat(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strncat" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || FT->getReturnType() != B.getInt8PtrTy() || + FT->getParamType(0) != FT->getReturnType() || + FT->getParamType(1) != FT->getReturnType() || + !FT->getParamType(2)->isIntegerTy()) + return nullptr; + + // Extract some information from the instruction. + Value *Dst = CI->getArgOperand(0); + Value *Src = CI->getArgOperand(1); + uint64_t Len; + + // We don't do anything if length is not constant. + if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getArgOperand(2))) + Len = LengthArg->getZExtValue(); + else + return nullptr; + + // See if we can get the length of the input string. + uint64_t SrcLen = GetStringLength(Src); + if (SrcLen == 0) + return nullptr; + --SrcLen; // Unbias length. + + // Handle the simple, do-nothing cases: + // strncat(x, "", c) -> x + // strncat(x, c, 0) -> x + if (SrcLen == 0 || Len == 0) + return Dst; + + // We don't optimize this case. + if (Len < SrcLen) + return nullptr; + + // strncat(x, s, c) -> strcat(x, s) + // s is constant so the strcat can be optimized further. + return emitStrLenMemCpy(Src, Dst, SrcLen, B); +} + +Value *LibCallSimplifier::optimizeStrChr(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strchr" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getReturnType() != B.getInt8PtrTy() || + FT->getParamType(0) != FT->getReturnType() || + !FT->getParamType(1)->isIntegerTy(32)) + return nullptr; + + Value *SrcStr = CI->getArgOperand(0); + + // If the second operand is non-constant, see if we can compute the length + // of the input string and turn this into memchr. + ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1)); + if (!CharC) { + uint64_t Len = GetStringLength(SrcStr); + if (Len == 0 || !FT->getParamType(1)->isIntegerTy(32)) // memchr needs i32. + return nullptr; + + return EmitMemChr(SrcStr, CI->getArgOperand(1), // include nul. + ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len), + B, DL, TLI); + } + + // Otherwise, the character is a constant, see if the first argument is + // a string literal. If so, we can constant fold. + StringRef Str; + if (!getConstantStringInfo(SrcStr, Str)) { + if (CharC->isZero()) // strchr(p, 0) -> p + strlen(p) + return B.CreateGEP(B.getInt8Ty(), SrcStr, EmitStrLen(SrcStr, B, DL, TLI), + "strchr"); + return nullptr; + } + + // Compute the offset, make sure to handle the case when we're searching for + // zero (a weird way to spell strlen). + size_t I = (0xFF & CharC->getSExtValue()) == 0 + ? Str.size() + : Str.find(CharC->getSExtValue()); + if (I == StringRef::npos) // Didn't find the char. strchr returns null. + return Constant::getNullValue(CI->getType()); + + // strchr(s+n,c) -> gep(s+n+i,c) + return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strchr"); +} + +Value *LibCallSimplifier::optimizeStrRChr(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strrchr" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getReturnType() != B.getInt8PtrTy() || + FT->getParamType(0) != FT->getReturnType() || + !FT->getParamType(1)->isIntegerTy(32)) + return nullptr; + + Value *SrcStr = CI->getArgOperand(0); + ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1)); + + // Cannot fold anything if we're not looking for a constant. + if (!CharC) + return nullptr; + + StringRef Str; + if (!getConstantStringInfo(SrcStr, Str)) { + // strrchr(s, 0) -> strchr(s, 0) + if (CharC->isZero()) + return EmitStrChr(SrcStr, '\0', B, TLI); + return nullptr; + } + + // Compute the offset. + size_t I = (0xFF & CharC->getSExtValue()) == 0 + ? Str.size() + : Str.rfind(CharC->getSExtValue()); + if (I == StringRef::npos) // Didn't find the char. Return null. + return Constant::getNullValue(CI->getType()); + + // strrchr(s+n,c) -> gep(s+n+i,c) + return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "strrchr"); +} + +Value *LibCallSimplifier::optimizeStrCmp(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strcmp" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !FT->getReturnType()->isIntegerTy(32) || + FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != B.getInt8PtrTy()) + return nullptr; + + Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1); + if (Str1P == Str2P) // strcmp(x,x) -> 0 + return ConstantInt::get(CI->getType(), 0); + + StringRef Str1, Str2; + bool HasStr1 = getConstantStringInfo(Str1P, Str1); + bool HasStr2 = getConstantStringInfo(Str2P, Str2); + + // strcmp(x, y) -> cnst (if both x and y are constant strings) + if (HasStr1 && HasStr2) + return ConstantInt::get(CI->getType(), Str1.compare(Str2)); + + if (HasStr1 && Str1.empty()) // strcmp("", x) -> -*x + return B.CreateNeg( + B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType())); + + if (HasStr2 && Str2.empty()) // strcmp(x,"") -> *x + return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType()); + + // strcmp(P, "x") -> memcmp(P, "x", 2) + uint64_t Len1 = GetStringLength(Str1P); + uint64_t Len2 = GetStringLength(Str2P); + if (Len1 && Len2) { + return EmitMemCmp(Str1P, Str2P, + ConstantInt::get(DL.getIntPtrType(CI->getContext()), + std::min(Len1, Len2)), + B, DL, TLI); + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrNCmp(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Verify the "strncmp" function prototype. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || !FT->getReturnType()->isIntegerTy(32) || + FT->getParamType(0) != FT->getParamType(1) || + FT->getParamType(0) != B.getInt8PtrTy() || + !FT->getParamType(2)->isIntegerTy()) + return nullptr; + + Value *Str1P = CI->getArgOperand(0), *Str2P = CI->getArgOperand(1); + if (Str1P == Str2P) // strncmp(x,x,n) -> 0 + return ConstantInt::get(CI->getType(), 0); + + // Get the length argument if it is constant. + uint64_t Length; + if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(CI->getArgOperand(2))) + Length = LengthArg->getZExtValue(); + else + return nullptr; + + if (Length == 0) // strncmp(x,y,0) -> 0 + return ConstantInt::get(CI->getType(), 0); + + if (Length == 1) // strncmp(x,y,1) -> memcmp(x,y,1) + return EmitMemCmp(Str1P, Str2P, CI->getArgOperand(2), B, DL, TLI); + + StringRef Str1, Str2; + bool HasStr1 = getConstantStringInfo(Str1P, Str1); + bool HasStr2 = getConstantStringInfo(Str2P, Str2); + + // strncmp(x, y) -> cnst (if both x and y are constant strings) + if (HasStr1 && HasStr2) { + StringRef SubStr1 = Str1.substr(0, Length); + StringRef SubStr2 = Str2.substr(0, Length); + return ConstantInt::get(CI->getType(), SubStr1.compare(SubStr2)); + } + + if (HasStr1 && Str1.empty()) // strncmp("", x, n) -> -*x + return B.CreateNeg( + B.CreateZExt(B.CreateLoad(Str2P, "strcmpload"), CI->getType())); + + if (HasStr2 && Str2.empty()) // strncmp(x, "", n) -> *x + return B.CreateZExt(B.CreateLoad(Str1P, "strcmpload"), CI->getType()); + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrCpy(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::strcpy)) + return nullptr; + + Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1); + if (Dst == Src) // strcpy(x,x) -> x + return Src; + + // See if we can get the length of the input string. + uint64_t Len = GetStringLength(Src); + if (Len == 0) + return nullptr; + + // We have enough information to now generate the memcpy call to do the + // copy for us. Make a memcpy to copy the nul byte with align = 1. + B.CreateMemCpy(Dst, Src, + ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len), 1); + return Dst; +} + +Value *LibCallSimplifier::optimizeStpCpy(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::stpcpy)) + return nullptr; + + Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1); + if (Dst == Src) { // stpcpy(x,x) -> x+strlen(x) + Value *StrLen = EmitStrLen(Src, B, DL, TLI); + return StrLen ? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, StrLen) : nullptr; + } + + // See if we can get the length of the input string. + uint64_t Len = GetStringLength(Src); + if (Len == 0) + return nullptr; + + Type *PT = Callee->getFunctionType()->getParamType(0); + Value *LenV = ConstantInt::get(DL.getIntPtrType(PT), Len); + Value *DstEnd = B.CreateGEP(B.getInt8Ty(), Dst, + ConstantInt::get(DL.getIntPtrType(PT), Len - 1)); + + // We have enough information to now generate the memcpy call to do the + // copy for us. Make a memcpy to copy the nul byte with align = 1. + B.CreateMemCpy(Dst, Src, LenV, 1); + return DstEnd; +} + +Value *LibCallSimplifier::optimizeStrNCpy(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::strncpy)) + return nullptr; + + Value *Dst = CI->getArgOperand(0); + Value *Src = CI->getArgOperand(1); + Value *LenOp = CI->getArgOperand(2); + + // See if we can get the length of the input string. + uint64_t SrcLen = GetStringLength(Src); + if (SrcLen == 0) + return nullptr; + --SrcLen; + + if (SrcLen == 0) { + // strncpy(x, "", y) -> memset(x, '\0', y, 1) + B.CreateMemSet(Dst, B.getInt8('\0'), LenOp, 1); + return Dst; + } + + uint64_t Len; + if (ConstantInt *LengthArg = dyn_cast<ConstantInt>(LenOp)) + Len = LengthArg->getZExtValue(); + else + return nullptr; + + if (Len == 0) + return Dst; // strncpy(x, y, 0) -> x + + // Let strncpy handle the zero padding + if (Len > SrcLen + 1) + return nullptr; + + Type *PT = Callee->getFunctionType()->getParamType(0); + // strncpy(x, s, c) -> memcpy(x, s, c, 1) [s and c are constant] + B.CreateMemCpy(Dst, Src, ConstantInt::get(DL.getIntPtrType(PT), Len), 1); + + return Dst; +} + +Value *LibCallSimplifier::optimizeStrLen(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 1 || FT->getParamType(0) != B.getInt8PtrTy() || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + Value *Src = CI->getArgOperand(0); + + // Constant folding: strlen("xyz") -> 3 + if (uint64_t Len = GetStringLength(Src)) + return ConstantInt::get(CI->getType(), Len - 1); + + // strlen(x?"foo":"bars") --> x ? 3 : 4 + if (SelectInst *SI = dyn_cast<SelectInst>(Src)) { + uint64_t LenTrue = GetStringLength(SI->getTrueValue()); + uint64_t LenFalse = GetStringLength(SI->getFalseValue()); + if (LenTrue && LenFalse) { + Function *Caller = CI->getParent()->getParent(); + emitOptimizationRemark(CI->getContext(), "simplify-libcalls", *Caller, + SI->getDebugLoc(), + "folded strlen(select) to select of constants"); + return B.CreateSelect(SI->getCondition(), + ConstantInt::get(CI->getType(), LenTrue - 1), + ConstantInt::get(CI->getType(), LenFalse - 1)); + } + } + + // strlen(x) != 0 --> *x != 0 + // strlen(x) == 0 --> *x == 0 + if (isOnlyUsedInZeroEqualityComparison(CI)) + return B.CreateZExt(B.CreateLoad(Src, "strlenfirst"), CI->getType()); + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrPBrk(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getParamType(0) != B.getInt8PtrTy() || + FT->getParamType(1) != FT->getParamType(0) || + FT->getReturnType() != FT->getParamType(0)) + return nullptr; + + StringRef S1, S2; + bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1); + bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2); + + // strpbrk(s, "") -> nullptr + // strpbrk("", s) -> nullptr + if ((HasS1 && S1.empty()) || (HasS2 && S2.empty())) + return Constant::getNullValue(CI->getType()); + + // Constant folding. + if (HasS1 && HasS2) { + size_t I = S1.find_first_of(S2); + if (I == StringRef::npos) // No match. + return Constant::getNullValue(CI->getType()); + + return B.CreateGEP(B.getInt8Ty(), CI->getArgOperand(0), B.getInt64(I), + "strpbrk"); + } + + // strpbrk(s, "a") -> strchr(s, 'a') + if (HasS2 && S2.size() == 1) + return EmitStrChr(CI->getArgOperand(0), S2[0], B, TLI); + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrTo(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if ((FT->getNumParams() != 2 && FT->getNumParams() != 3) || + !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy()) + return nullptr; + + Value *EndPtr = CI->getArgOperand(1); + if (isa<ConstantPointerNull>(EndPtr)) { + // With a null EndPtr, this function won't capture the main argument. + // It would be readonly too, except that it still may write to errno. + CI->addAttribute(1, Attribute::NoCapture); + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrSpn(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getParamType(0) != B.getInt8PtrTy() || + FT->getParamType(1) != FT->getParamType(0) || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + StringRef S1, S2; + bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1); + bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2); + + // strspn(s, "") -> 0 + // strspn("", s) -> 0 + if ((HasS1 && S1.empty()) || (HasS2 && S2.empty())) + return Constant::getNullValue(CI->getType()); + + // Constant folding. + if (HasS1 && HasS2) { + size_t Pos = S1.find_first_not_of(S2); + if (Pos == StringRef::npos) + Pos = S1.size(); + return ConstantInt::get(CI->getType(), Pos); + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrCSpn(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getParamType(0) != B.getInt8PtrTy() || + FT->getParamType(1) != FT->getParamType(0) || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + StringRef S1, S2; + bool HasS1 = getConstantStringInfo(CI->getArgOperand(0), S1); + bool HasS2 = getConstantStringInfo(CI->getArgOperand(1), S2); + + // strcspn("", s) -> 0 + if (HasS1 && S1.empty()) + return Constant::getNullValue(CI->getType()); + + // Constant folding. + if (HasS1 && HasS2) { + size_t Pos = S1.find_first_of(S2); + if (Pos == StringRef::npos) + Pos = S1.size(); + return ConstantInt::get(CI->getType(), Pos); + } + + // strcspn(s, "") -> strlen(s) + if (HasS2 && S2.empty()) + return EmitStrLen(CI->getArgOperand(0), B, DL, TLI); + + return nullptr; +} + +Value *LibCallSimplifier::optimizeStrStr(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || + !FT->getReturnType()->isPointerTy()) + return nullptr; + + // fold strstr(x, x) -> x. + if (CI->getArgOperand(0) == CI->getArgOperand(1)) + return B.CreateBitCast(CI->getArgOperand(0), CI->getType()); + + // fold strstr(a, b) == a -> strncmp(a, b, strlen(b)) == 0 + if (isOnlyUsedInEqualityComparison(CI, CI->getArgOperand(0))) { + Value *StrLen = EmitStrLen(CI->getArgOperand(1), B, DL, TLI); + if (!StrLen) + return nullptr; + Value *StrNCmp = EmitStrNCmp(CI->getArgOperand(0), CI->getArgOperand(1), + StrLen, B, DL, TLI); + if (!StrNCmp) + return nullptr; + for (auto UI = CI->user_begin(), UE = CI->user_end(); UI != UE;) { + ICmpInst *Old = cast<ICmpInst>(*UI++); + Value *Cmp = + B.CreateICmp(Old->getPredicate(), StrNCmp, + ConstantInt::getNullValue(StrNCmp->getType()), "cmp"); + replaceAllUsesWith(Old, Cmp); + } + return CI; + } + + // See if either input string is a constant string. + StringRef SearchStr, ToFindStr; + bool HasStr1 = getConstantStringInfo(CI->getArgOperand(0), SearchStr); + bool HasStr2 = getConstantStringInfo(CI->getArgOperand(1), ToFindStr); + + // fold strstr(x, "") -> x. + if (HasStr2 && ToFindStr.empty()) + return B.CreateBitCast(CI->getArgOperand(0), CI->getType()); + + // If both strings are known, constant fold it. + if (HasStr1 && HasStr2) { + size_t Offset = SearchStr.find(ToFindStr); + + if (Offset == StringRef::npos) // strstr("foo", "bar") -> null + return Constant::getNullValue(CI->getType()); + + // strstr("abcd", "bc") -> gep((char*)"abcd", 1) + Value *Result = CastToCStr(CI->getArgOperand(0), B); + Result = B.CreateConstInBoundsGEP1_64(Result, Offset, "strstr"); + return B.CreateBitCast(Result, CI->getType()); + } + + // fold strstr(x, "y") -> strchr(x, 'y'). + if (HasStr2 && ToFindStr.size() == 1) { + Value *StrChr = EmitStrChr(CI->getArgOperand(0), ToFindStr[0], B, TLI); + return StrChr ? B.CreateBitCast(StrChr, CI->getType()) : nullptr; + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeMemChr(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isIntegerTy(32) || + !FT->getParamType(2)->isIntegerTy() || + !FT->getReturnType()->isPointerTy()) + return nullptr; + + Value *SrcStr = CI->getArgOperand(0); + ConstantInt *CharC = dyn_cast<ConstantInt>(CI->getArgOperand(1)); + ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getArgOperand(2)); + + // memchr(x, y, 0) -> null + if (LenC && LenC->isNullValue()) + return Constant::getNullValue(CI->getType()); + + // From now on we need at least constant length and string. + StringRef Str; + if (!LenC || !getConstantStringInfo(SrcStr, Str, 0, /*TrimAtNul=*/false)) + return nullptr; + + // Truncate the string to LenC. If Str is smaller than LenC we will still only + // scan the string, as reading past the end of it is undefined and we can just + // return null if we don't find the char. + Str = Str.substr(0, LenC->getZExtValue()); + + // If the char is variable but the input str and length are not we can turn + // this memchr call into a simple bit field test. Of course this only works + // when the return value is only checked against null. + // + // It would be really nice to reuse switch lowering here but we can't change + // the CFG at this point. + // + // memchr("\r\n", C, 2) != nullptr -> (C & ((1 << '\r') | (1 << '\n'))) != 0 + // after bounds check. + if (!CharC && !Str.empty() && isOnlyUsedInZeroEqualityComparison(CI)) { + unsigned char Max = + *std::max_element(reinterpret_cast<const unsigned char *>(Str.begin()), + reinterpret_cast<const unsigned char *>(Str.end())); + + // Make sure the bit field we're about to create fits in a register on the + // target. + // FIXME: On a 64 bit architecture this prevents us from using the + // interesting range of alpha ascii chars. We could do better by emitting + // two bitfields or shifting the range by 64 if no lower chars are used. + if (!DL.fitsInLegalInteger(Max + 1)) + return nullptr; + + // For the bit field use a power-of-2 type with at least 8 bits to avoid + // creating unnecessary illegal types. + unsigned char Width = NextPowerOf2(std::max((unsigned char)7, Max)); + + // Now build the bit field. + APInt Bitfield(Width, 0); + for (char C : Str) + Bitfield.setBit((unsigned char)C); + Value *BitfieldC = B.getInt(Bitfield); + + // First check that the bit field access is within bounds. + Value *C = B.CreateZExtOrTrunc(CI->getArgOperand(1), BitfieldC->getType()); + Value *Bounds = B.CreateICmp(ICmpInst::ICMP_ULT, C, B.getIntN(Width, Width), + "memchr.bounds"); + + // Create code that checks if the given bit is set in the field. + Value *Shl = B.CreateShl(B.getIntN(Width, 1ULL), C); + Value *Bits = B.CreateIsNotNull(B.CreateAnd(Shl, BitfieldC), "memchr.bits"); + + // Finally merge both checks and cast to pointer type. The inttoptr + // implicitly zexts the i1 to intptr type. + return B.CreateIntToPtr(B.CreateAnd(Bounds, Bits, "memchr"), CI->getType()); + } + + // Check if all arguments are constants. If so, we can constant fold. + if (!CharC) + return nullptr; + + // Compute the offset. + size_t I = Str.find(CharC->getSExtValue() & 0xFF); + if (I == StringRef::npos) // Didn't find the char. memchr returns null. + return Constant::getNullValue(CI->getType()); + + // memchr(s+n,c,l) -> gep(s+n+i,c) + return B.CreateGEP(B.getInt8Ty(), SrcStr, B.getInt64(I), "memchr"); +} + +Value *LibCallSimplifier::optimizeMemCmp(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 3 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || + !FT->getReturnType()->isIntegerTy(32)) + return nullptr; + + Value *LHS = CI->getArgOperand(0), *RHS = CI->getArgOperand(1); + + if (LHS == RHS) // memcmp(s,s,x) -> 0 + return Constant::getNullValue(CI->getType()); + + // Make sure we have a constant length. + ConstantInt *LenC = dyn_cast<ConstantInt>(CI->getArgOperand(2)); + if (!LenC) + return nullptr; + uint64_t Len = LenC->getZExtValue(); + + if (Len == 0) // memcmp(s1,s2,0) -> 0 + return Constant::getNullValue(CI->getType()); + + // memcmp(S1,S2,1) -> *(unsigned char*)LHS - *(unsigned char*)RHS + if (Len == 1) { + Value *LHSV = B.CreateZExt(B.CreateLoad(CastToCStr(LHS, B), "lhsc"), + CI->getType(), "lhsv"); + Value *RHSV = B.CreateZExt(B.CreateLoad(CastToCStr(RHS, B), "rhsc"), + CI->getType(), "rhsv"); + return B.CreateSub(LHSV, RHSV, "chardiff"); + } + + // memcmp(S1,S2,N/8)==0 -> (*(intN_t*)S1 != *(intN_t*)S2)==0 + if (DL.isLegalInteger(Len * 8) && isOnlyUsedInZeroEqualityComparison(CI)) { + + IntegerType *IntType = IntegerType::get(CI->getContext(), Len * 8); + unsigned PrefAlignment = DL.getPrefTypeAlignment(IntType); + + if (getKnownAlignment(LHS, DL, CI) >= PrefAlignment && + getKnownAlignment(RHS, DL, CI) >= PrefAlignment) { + + Type *LHSPtrTy = + IntType->getPointerTo(LHS->getType()->getPointerAddressSpace()); + Type *RHSPtrTy = + IntType->getPointerTo(RHS->getType()->getPointerAddressSpace()); + + Value *LHSV = + B.CreateLoad(B.CreateBitCast(LHS, LHSPtrTy, "lhsc"), "lhsv"); + Value *RHSV = + B.CreateLoad(B.CreateBitCast(RHS, RHSPtrTy, "rhsc"), "rhsv"); + + return B.CreateZExt(B.CreateICmpNE(LHSV, RHSV), CI->getType(), "memcmp"); + } + } + + // Constant folding: memcmp(x, y, l) -> cnst (all arguments are constant) + StringRef LHSStr, RHSStr; + if (getConstantStringInfo(LHS, LHSStr) && + getConstantStringInfo(RHS, RHSStr)) { + // Make sure we're not reading out-of-bounds memory. + if (Len > LHSStr.size() || Len > RHSStr.size()) + return nullptr; + // Fold the memcmp and normalize the result. This way we get consistent + // results across multiple platforms. + uint64_t Ret = 0; + int Cmp = memcmp(LHSStr.data(), RHSStr.data(), Len); + if (Cmp < 0) + Ret = -1; + else if (Cmp > 0) + Ret = 1; + return ConstantInt::get(CI->getType(), Ret); + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeMemCpy(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memcpy)) + return nullptr; + + // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1) + B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1), + CI->getArgOperand(2), 1); + return CI->getArgOperand(0); +} + +Value *LibCallSimplifier::optimizeMemMove(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memmove)) + return nullptr; + + // memmove(x, y, n) -> llvm.memmove(x, y, n, 1) + B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1), + CI->getArgOperand(2), 1); + return CI->getArgOperand(0); +} + +Value *LibCallSimplifier::optimizeMemSet(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memset)) + return nullptr; + + // memset(p, v, n) -> llvm.memset(p, v, n, 1) + Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false); + B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1); + return CI->getArgOperand(0); +} + +//===----------------------------------------------------------------------===// +// Math Library Optimizations +//===----------------------------------------------------------------------===// + +/// Return a variant of Val with float type. +/// Currently this works in two cases: If Val is an FPExtension of a float +/// value to something bigger, simply return the operand. +/// If Val is a ConstantFP but can be converted to a float ConstantFP without +/// loss of precision do so. +static Value *valueHasFloatPrecision(Value *Val) { + if (FPExtInst *Cast = dyn_cast<FPExtInst>(Val)) { + Value *Op = Cast->getOperand(0); + if (Op->getType()->isFloatTy()) + return Op; + } + if (ConstantFP *Const = dyn_cast<ConstantFP>(Val)) { + APFloat F = Const->getValueAPF(); + bool losesInfo; + (void)F.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven, + &losesInfo); + if (!losesInfo) + return ConstantFP::get(Const->getContext(), F); + } + return nullptr; +} + +//===----------------------------------------------------------------------===// +// Double -> Float Shrinking Optimizations for Unary Functions like 'floor' + +Value *LibCallSimplifier::optimizeUnaryDoubleFP(CallInst *CI, IRBuilder<> &B, + bool CheckRetType) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 1 || !FT->getReturnType()->isDoubleTy() || + !FT->getParamType(0)->isDoubleTy()) + return nullptr; + + if (CheckRetType) { + // Check if all the uses for function like 'sin' are converted to float. + for (User *U : CI->users()) { + FPTruncInst *Cast = dyn_cast<FPTruncInst>(U); + if (!Cast || !Cast->getType()->isFloatTy()) + return nullptr; + } + } + + // If this is something like 'floor((double)floatval)', convert to floorf. + Value *V = valueHasFloatPrecision(CI->getArgOperand(0)); + if (V == nullptr) + return nullptr; + + // Propagate fast-math flags from the existing call to the new call. + IRBuilder<>::FastMathFlagGuard Guard(B); + B.setFastMathFlags(CI->getFastMathFlags()); + + // floor((double)floatval) -> (double)floorf(floatval) + if (Callee->isIntrinsic()) { + Module *M = CI->getModule(); + Intrinsic::ID IID = Callee->getIntrinsicID(); + Function *F = Intrinsic::getDeclaration(M, IID, B.getFloatTy()); + V = B.CreateCall(F, V); + } else { + // The call is a library call rather than an intrinsic. + V = EmitUnaryFloatFnCall(V, Callee->getName(), B, Callee->getAttributes()); + } + + return B.CreateFPExt(V, B.getDoubleTy()); +} + +// Double -> Float Shrinking Optimizations for Binary Functions like 'fmin/fmax' +Value *LibCallSimplifier::optimizeBinaryDoubleFP(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 2 arguments of the same FP type, which match the + // result type. + if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != FT->getParamType(1) || + !FT->getParamType(0)->isFloatingPointTy()) + return nullptr; + + // If this is something like 'fmin((double)floatval1, (double)floatval2)', + // or fmin(1.0, (double)floatval), then we convert it to fminf. + Value *V1 = valueHasFloatPrecision(CI->getArgOperand(0)); + if (V1 == nullptr) + return nullptr; + Value *V2 = valueHasFloatPrecision(CI->getArgOperand(1)); + if (V2 == nullptr) + return nullptr; + + // Propagate fast-math flags from the existing call to the new call. + IRBuilder<>::FastMathFlagGuard Guard(B); + B.setFastMathFlags(CI->getFastMathFlags()); + + // fmin((double)floatval1, (double)floatval2) + // -> (double)fminf(floatval1, floatval2) + // TODO: Handle intrinsics in the same way as in optimizeUnaryDoubleFP(). + Value *V = EmitBinaryFloatFnCall(V1, V2, Callee->getName(), B, + Callee->getAttributes()); + return B.CreateFPExt(V, B.getDoubleTy()); +} + +Value *LibCallSimplifier::optimizeCos(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (UnsafeFPShrink && Name == "cos" && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + + FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 1 argument of FP type, which matches the + // result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + // cos(-x) -> cos(x) + Value *Op1 = CI->getArgOperand(0); + if (BinaryOperator::isFNeg(Op1)) { + BinaryOperator *BinExpr = cast<BinaryOperator>(Op1); + return B.CreateCall(Callee, BinExpr->getOperand(1), "cos"); + } + return Ret; +} + +static Value *getPow(Value *InnerChain[33], unsigned Exp, IRBuilder<> &B) { + // Multiplications calculated using Addition Chains. + // Refer: http://wwwhomes.uni-bielefeld.de/achim/addition_chain.html + + assert(Exp != 0 && "Incorrect exponent 0 not handled"); + + if (InnerChain[Exp]) + return InnerChain[Exp]; + + static const unsigned AddChain[33][2] = { + {0, 0}, // Unused. + {0, 0}, // Unused (base case = pow1). + {1, 1}, // Unused (pre-computed). + {1, 2}, {2, 2}, {2, 3}, {3, 3}, {2, 5}, {4, 4}, + {1, 8}, {5, 5}, {1, 10}, {6, 6}, {4, 9}, {7, 7}, + {3, 12}, {8, 8}, {8, 9}, {2, 16}, {1, 18}, {10, 10}, + {6, 15}, {11, 11}, {3, 20}, {12, 12}, {8, 17}, {13, 13}, + {3, 24}, {14, 14}, {4, 25}, {15, 15}, {3, 28}, {16, 16}, + }; + + InnerChain[Exp] = B.CreateFMul(getPow(InnerChain, AddChain[Exp][0], B), + getPow(InnerChain, AddChain[Exp][1], B)); + return InnerChain[Exp]; +} + +Value *LibCallSimplifier::optimizePow(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (UnsafeFPShrink && Name == "pow" && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + + FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 2 arguments of the same FP type, which match the + // result type. + if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != FT->getParamType(1) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + Value *Op1 = CI->getArgOperand(0), *Op2 = CI->getArgOperand(1); + if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) { + // pow(1.0, x) -> 1.0 + if (Op1C->isExactlyValue(1.0)) + return Op1C; + // pow(2.0, x) -> exp2(x) + if (Op1C->isExactlyValue(2.0) && + hasUnaryFloatFn(TLI, Op1->getType(), LibFunc::exp2, LibFunc::exp2f, + LibFunc::exp2l)) + return EmitUnaryFloatFnCall(Op2, TLI->getName(LibFunc::exp2), B, + Callee->getAttributes()); + // pow(10.0, x) -> exp10(x) + if (Op1C->isExactlyValue(10.0) && + hasUnaryFloatFn(TLI, Op1->getType(), LibFunc::exp10, LibFunc::exp10f, + LibFunc::exp10l)) + return EmitUnaryFloatFnCall(Op2, TLI->getName(LibFunc::exp10), B, + Callee->getAttributes()); + } + + // FIXME: Use instruction-level FMF. + bool UnsafeFPMath = canUseUnsafeFPMath(CI->getParent()->getParent()); + + // pow(exp(x), y) -> exp(x * y) + // pow(exp2(x), y) -> exp2(x * y) + // We enable these only with fast-math. Besides rounding differences, the + // transformation changes overflow and underflow behavior quite dramatically. + // Example: x = 1000, y = 0.001. + // pow(exp(x), y) = pow(inf, 0.001) = inf, whereas exp(x*y) = exp(1). + auto *OpC = dyn_cast<CallInst>(Op1); + if (OpC && OpC->hasUnsafeAlgebra() && CI->hasUnsafeAlgebra()) { + LibFunc::Func Func; + Function *OpCCallee = OpC->getCalledFunction(); + if (OpCCallee && TLI->getLibFunc(OpCCallee->getName(), Func) && + TLI->has(Func) && (Func == LibFunc::exp || Func == LibFunc::exp2)) { + IRBuilder<>::FastMathFlagGuard Guard(B); + B.setFastMathFlags(CI->getFastMathFlags()); + Value *FMul = B.CreateFMul(OpC->getArgOperand(0), Op2, "mul"); + return EmitUnaryFloatFnCall(FMul, OpCCallee->getName(), B, + OpCCallee->getAttributes()); + } + } + + ConstantFP *Op2C = dyn_cast<ConstantFP>(Op2); + if (!Op2C) + return Ret; + + if (Op2C->getValueAPF().isZero()) // pow(x, 0.0) -> 1.0 + return ConstantFP::get(CI->getType(), 1.0); + + if (Op2C->isExactlyValue(0.5) && + hasUnaryFloatFn(TLI, Op2->getType(), LibFunc::sqrt, LibFunc::sqrtf, + LibFunc::sqrtl) && + hasUnaryFloatFn(TLI, Op2->getType(), LibFunc::fabs, LibFunc::fabsf, + LibFunc::fabsl)) { + + // In -ffast-math, pow(x, 0.5) -> sqrt(x). + if (CI->hasUnsafeAlgebra()) { + IRBuilder<>::FastMathFlagGuard Guard(B); + B.setFastMathFlags(CI->getFastMathFlags()); + return EmitUnaryFloatFnCall(Op1, TLI->getName(LibFunc::sqrt), B, + Callee->getAttributes()); + } + + // Expand pow(x, 0.5) to (x == -infinity ? +infinity : fabs(sqrt(x))). + // This is faster than calling pow, and still handles negative zero + // and negative infinity correctly. + // TODO: In finite-only mode, this could be just fabs(sqrt(x)). + Value *Inf = ConstantFP::getInfinity(CI->getType()); + Value *NegInf = ConstantFP::getInfinity(CI->getType(), true); + Value *Sqrt = EmitUnaryFloatFnCall(Op1, "sqrt", B, Callee->getAttributes()); + Value *FAbs = + EmitUnaryFloatFnCall(Sqrt, "fabs", B, Callee->getAttributes()); + Value *FCmp = B.CreateFCmpOEQ(Op1, NegInf); + Value *Sel = B.CreateSelect(FCmp, Inf, FAbs); + return Sel; + } + + if (Op2C->isExactlyValue(1.0)) // pow(x, 1.0) -> x + return Op1; + if (Op2C->isExactlyValue(2.0)) // pow(x, 2.0) -> x*x + return B.CreateFMul(Op1, Op1, "pow2"); + if (Op2C->isExactlyValue(-1.0)) // pow(x, -1.0) -> 1.0/x + return B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), Op1, "powrecip"); + + // In -ffast-math, generate repeated fmul instead of generating pow(x, n). + if (UnsafeFPMath) { + APFloat V = abs(Op2C->getValueAPF()); + // We limit to a max of 7 fmul(s). Thus max exponent is 32. + // This transformation applies to integer exponents only. + if (V.compare(APFloat(V.getSemantics(), 32.0)) == APFloat::cmpGreaterThan || + !V.isInteger()) + return nullptr; + + // We will memoize intermediate products of the Addition Chain. + Value *InnerChain[33] = {nullptr}; + InnerChain[1] = Op1; + InnerChain[2] = B.CreateFMul(Op1, Op1); + + // We cannot readily convert a non-double type (like float) to a double. + // So we first convert V to something which could be converted to double. + bool ignored; + V.convert(APFloat::IEEEdouble, APFloat::rmTowardZero, &ignored); + Value *FMul = getPow(InnerChain, V.convertToDouble(), B); + // For negative exponents simply compute the reciprocal. + if (Op2C->isNegative()) + FMul = B.CreateFDiv(ConstantFP::get(CI->getType(), 1.0), FMul); + return FMul; + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeExp2(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Function *Caller = CI->getParent()->getParent(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (UnsafeFPShrink && Name == "exp2" && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + + FunctionType *FT = Callee->getFunctionType(); + // Just make sure this has 1 argument of FP type, which matches the + // result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + Value *Op = CI->getArgOperand(0); + // Turn exp2(sitofp(x)) -> ldexp(1.0, sext(x)) if sizeof(x) <= 32 + // Turn exp2(uitofp(x)) -> ldexp(1.0, zext(x)) if sizeof(x) < 32 + LibFunc::Func LdExp = LibFunc::ldexpl; + if (Op->getType()->isFloatTy()) + LdExp = LibFunc::ldexpf; + else if (Op->getType()->isDoubleTy()) + LdExp = LibFunc::ldexp; + + if (TLI->has(LdExp)) { + Value *LdExpArg = nullptr; + if (SIToFPInst *OpC = dyn_cast<SIToFPInst>(Op)) { + if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() <= 32) + LdExpArg = B.CreateSExt(OpC->getOperand(0), B.getInt32Ty()); + } else if (UIToFPInst *OpC = dyn_cast<UIToFPInst>(Op)) { + if (OpC->getOperand(0)->getType()->getPrimitiveSizeInBits() < 32) + LdExpArg = B.CreateZExt(OpC->getOperand(0), B.getInt32Ty()); + } + + if (LdExpArg) { + Constant *One = ConstantFP::get(CI->getContext(), APFloat(1.0f)); + if (!Op->getType()->isFloatTy()) + One = ConstantExpr::getFPExtend(One, Op->getType()); + + Module *M = Caller->getParent(); + Value *Callee = + M->getOrInsertFunction(TLI->getName(LdExp), Op->getType(), + Op->getType(), B.getInt32Ty(), nullptr); + CallInst *CI = B.CreateCall(Callee, {One, LdExpArg}); + if (const Function *F = dyn_cast<Function>(Callee->stripPointerCasts())) + CI->setCallingConv(F->getCallingConv()); + + return CI; + } + } + return Ret; +} + +Value *LibCallSimplifier::optimizeFabs(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (Name == "fabs" && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, false); + + FunctionType *FT = Callee->getFunctionType(); + // Make sure this has 1 argument of FP type which matches the result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + Value *Op = CI->getArgOperand(0); + if (Instruction *I = dyn_cast<Instruction>(Op)) { + // Fold fabs(x * x) -> x * x; any squared FP value must already be positive. + if (I->getOpcode() == Instruction::FMul) + if (I->getOperand(0) == I->getOperand(1)) + return Op; + } + return Ret; +} + +Value *LibCallSimplifier::optimizeFMinFMax(CallInst *CI, IRBuilder<> &B) { + // If we can shrink the call to a float function rather than a double + // function, do that first. + Function *Callee = CI->getCalledFunction(); + StringRef Name = Callee->getName(); + if ((Name == "fmin" || Name == "fmax") && hasFloatVersion(Name)) + if (Value *Ret = optimizeBinaryDoubleFP(CI, B)) + return Ret; + + // Make sure this has 2 arguments of FP type which match the result type. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || FT->getReturnType() != FT->getParamType(0) || + FT->getParamType(0) != FT->getParamType(1) || + !FT->getParamType(0)->isFloatingPointTy()) + return nullptr; + + IRBuilder<>::FastMathFlagGuard Guard(B); + FastMathFlags FMF; + if (CI->hasUnsafeAlgebra()) { + // Unsafe algebra sets all fast-math-flags to true. + FMF.setUnsafeAlgebra(); + } else { + // At a minimum, no-nans-fp-math must be true. + if (!CI->hasNoNaNs()) + return nullptr; + // No-signed-zeros is implied by the definitions of fmax/fmin themselves: + // "Ideally, fmax would be sensitive to the sign of zero, for example + // fmax(-0. 0, +0. 0) would return +0; however, implementation in software + // might be impractical." + FMF.setNoSignedZeros(); + FMF.setNoNaNs(); + } + B.setFastMathFlags(FMF); + + // We have a relaxed floating-point environment. We can ignore NaN-handling + // and transform to a compare and select. We do not have to consider errno or + // exceptions, because fmin/fmax do not have those. + Value *Op0 = CI->getArgOperand(0); + Value *Op1 = CI->getArgOperand(1); + Value *Cmp = Callee->getName().startswith("fmin") ? + B.CreateFCmpOLT(Op0, Op1) : B.CreateFCmpOGT(Op0, Op1); + return B.CreateSelect(Cmp, Op0, Op1); +} + +Value *LibCallSimplifier::optimizeLog(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (UnsafeFPShrink && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + FunctionType *FT = Callee->getFunctionType(); + + // Just make sure this has 1 argument of FP type, which matches the + // result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + if (!CI->hasUnsafeAlgebra()) + return Ret; + Value *Op1 = CI->getArgOperand(0); + auto *OpC = dyn_cast<CallInst>(Op1); + + // The earlier call must also be unsafe in order to do these transforms. + if (!OpC || !OpC->hasUnsafeAlgebra()) + return Ret; + + // log(pow(x,y)) -> y*log(x) + // This is only applicable to log, log2, log10. + if (Name != "log" && Name != "log2" && Name != "log10") + return Ret; + + IRBuilder<>::FastMathFlagGuard Guard(B); + FastMathFlags FMF; + FMF.setUnsafeAlgebra(); + B.setFastMathFlags(FMF); + + LibFunc::Func Func; + Function *F = OpC->getCalledFunction(); + if (F && ((TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) && + Func == LibFunc::pow) || F->getIntrinsicID() == Intrinsic::pow)) + return B.CreateFMul(OpC->getArgOperand(1), + EmitUnaryFloatFnCall(OpC->getOperand(0), Callee->getName(), B, + Callee->getAttributes()), "mul"); + + // log(exp2(y)) -> y*log(2) + if (F && Name == "log" && TLI->getLibFunc(F->getName(), Func) && + TLI->has(Func) && Func == LibFunc::exp2) + return B.CreateFMul( + OpC->getArgOperand(0), + EmitUnaryFloatFnCall(ConstantFP::get(CI->getType(), 2.0), + Callee->getName(), B, Callee->getAttributes()), + "logmul"); + return Ret; +} + +Value *LibCallSimplifier::optimizeSqrt(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + Value *Ret = nullptr; + if (TLI->has(LibFunc::sqrtf) && (Callee->getName() == "sqrt" || + Callee->getIntrinsicID() == Intrinsic::sqrt)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + + if (!CI->hasUnsafeAlgebra()) + return Ret; + + Instruction *I = dyn_cast<Instruction>(CI->getArgOperand(0)); + if (!I || I->getOpcode() != Instruction::FMul || !I->hasUnsafeAlgebra()) + return Ret; + + // We're looking for a repeated factor in a multiplication tree, + // so we can do this fold: sqrt(x * x) -> fabs(x); + // or this fold: sqrt((x * x) * y) -> fabs(x) * sqrt(y). + Value *Op0 = I->getOperand(0); + Value *Op1 = I->getOperand(1); + Value *RepeatOp = nullptr; + Value *OtherOp = nullptr; + if (Op0 == Op1) { + // Simple match: the operands of the multiply are identical. + RepeatOp = Op0; + } else { + // Look for a more complicated pattern: one of the operands is itself + // a multiply, so search for a common factor in that multiply. + // Note: We don't bother looking any deeper than this first level or for + // variations of this pattern because instcombine's visitFMUL and/or the + // reassociation pass should give us this form. + Value *OtherMul0, *OtherMul1; + if (match(Op0, m_FMul(m_Value(OtherMul0), m_Value(OtherMul1)))) { + // Pattern: sqrt((x * y) * z) + if (OtherMul0 == OtherMul1 && + cast<Instruction>(Op0)->hasUnsafeAlgebra()) { + // Matched: sqrt((x * x) * z) + RepeatOp = OtherMul0; + OtherOp = Op1; + } + } + } + if (!RepeatOp) + return Ret; + + // Fast math flags for any created instructions should match the sqrt + // and multiply. + IRBuilder<>::FastMathFlagGuard Guard(B); + B.setFastMathFlags(I->getFastMathFlags()); + + // If we found a repeated factor, hoist it out of the square root and + // replace it with the fabs of that factor. + Module *M = Callee->getParent(); + Type *ArgType = I->getType(); + Value *Fabs = Intrinsic::getDeclaration(M, Intrinsic::fabs, ArgType); + Value *FabsCall = B.CreateCall(Fabs, RepeatOp, "fabs"); + if (OtherOp) { + // If we found a non-repeated factor, we still need to get its square + // root. We then multiply that by the value that was simplified out + // of the square root calculation. + Value *Sqrt = Intrinsic::getDeclaration(M, Intrinsic::sqrt, ArgType); + Value *SqrtCall = B.CreateCall(Sqrt, OtherOp, "sqrt"); + return B.CreateFMul(FabsCall, SqrtCall); + } + return FabsCall; +} + +// TODO: Generalize to handle any trig function and its inverse. +Value *LibCallSimplifier::optimizeTan(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + Value *Ret = nullptr; + StringRef Name = Callee->getName(); + if (UnsafeFPShrink && Name == "tan" && hasFloatVersion(Name)) + Ret = optimizeUnaryDoubleFP(CI, B, true); + FunctionType *FT = Callee->getFunctionType(); + + // Just make sure this has 1 argument of FP type, which matches the + // result type. + if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) || + !FT->getParamType(0)->isFloatingPointTy()) + return Ret; + + Value *Op1 = CI->getArgOperand(0); + auto *OpC = dyn_cast<CallInst>(Op1); + if (!OpC) + return Ret; + + // Both calls must allow unsafe optimizations in order to remove them. + if (!CI->hasUnsafeAlgebra() || !OpC->hasUnsafeAlgebra()) + return Ret; + + // tan(atan(x)) -> x + // tanf(atanf(x)) -> x + // tanl(atanl(x)) -> x + LibFunc::Func Func; + Function *F = OpC->getCalledFunction(); + if (F && TLI->getLibFunc(F->getName(), Func) && TLI->has(Func) && + ((Func == LibFunc::atan && Callee->getName() == "tan") || + (Func == LibFunc::atanf && Callee->getName() == "tanf") || + (Func == LibFunc::atanl && Callee->getName() == "tanl"))) + Ret = OpC->getArgOperand(0); + return Ret; +} + +static bool isTrigLibCall(CallInst *CI); +static void insertSinCosCall(IRBuilder<> &B, Function *OrigCallee, Value *Arg, + bool UseFloat, Value *&Sin, Value *&Cos, + Value *&SinCos); + +Value *LibCallSimplifier::optimizeSinCosPi(CallInst *CI, IRBuilder<> &B) { + + // Make sure the prototype is as expected, otherwise the rest of the + // function is probably invalid and likely to abort. + if (!isTrigLibCall(CI)) + return nullptr; + + Value *Arg = CI->getArgOperand(0); + SmallVector<CallInst *, 1> SinCalls; + SmallVector<CallInst *, 1> CosCalls; + SmallVector<CallInst *, 1> SinCosCalls; + + bool IsFloat = Arg->getType()->isFloatTy(); + + // Look for all compatible sinpi, cospi and sincospi calls with the same + // argument. If there are enough (in some sense) we can make the + // substitution. + for (User *U : Arg->users()) + classifyArgUse(U, CI->getParent(), IsFloat, SinCalls, CosCalls, + SinCosCalls); + + // It's only worthwhile if both sinpi and cospi are actually used. + if (SinCosCalls.empty() && (SinCalls.empty() || CosCalls.empty())) + return nullptr; + + Value *Sin, *Cos, *SinCos; + insertSinCosCall(B, CI->getCalledFunction(), Arg, IsFloat, Sin, Cos, SinCos); + + replaceTrigInsts(SinCalls, Sin); + replaceTrigInsts(CosCalls, Cos); + replaceTrigInsts(SinCosCalls, SinCos); + + return nullptr; +} + +static bool isTrigLibCall(CallInst *CI) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + + // We can only hope to do anything useful if we can ignore things like errno + // and floating-point exceptions. + bool AttributesSafe = + CI->hasFnAttr(Attribute::NoUnwind) && CI->hasFnAttr(Attribute::ReadNone); + + // Other than that we need float(float) or double(double) + return AttributesSafe && FT->getNumParams() == 1 && + FT->getReturnType() == FT->getParamType(0) && + (FT->getParamType(0)->isFloatTy() || + FT->getParamType(0)->isDoubleTy()); +} + +void +LibCallSimplifier::classifyArgUse(Value *Val, BasicBlock *BB, bool IsFloat, + SmallVectorImpl<CallInst *> &SinCalls, + SmallVectorImpl<CallInst *> &CosCalls, + SmallVectorImpl<CallInst *> &SinCosCalls) { + CallInst *CI = dyn_cast<CallInst>(Val); + + if (!CI) + return; + + Function *Callee = CI->getCalledFunction(); + LibFunc::Func Func; + if (!Callee || !TLI->getLibFunc(Callee->getName(), Func) || !TLI->has(Func) || + !isTrigLibCall(CI)) + return; + + if (IsFloat) { + if (Func == LibFunc::sinpif) + SinCalls.push_back(CI); + else if (Func == LibFunc::cospif) + CosCalls.push_back(CI); + else if (Func == LibFunc::sincospif_stret) + SinCosCalls.push_back(CI); + } else { + if (Func == LibFunc::sinpi) + SinCalls.push_back(CI); + else if (Func == LibFunc::cospi) + CosCalls.push_back(CI); + else if (Func == LibFunc::sincospi_stret) + SinCosCalls.push_back(CI); + } +} + +void LibCallSimplifier::replaceTrigInsts(SmallVectorImpl<CallInst *> &Calls, + Value *Res) { + for (CallInst *C : Calls) + replaceAllUsesWith(C, Res); +} + +void insertSinCosCall(IRBuilder<> &B, Function *OrigCallee, Value *Arg, + bool UseFloat, Value *&Sin, Value *&Cos, Value *&SinCos) { + Type *ArgTy = Arg->getType(); + Type *ResTy; + StringRef Name; + + Triple T(OrigCallee->getParent()->getTargetTriple()); + if (UseFloat) { + Name = "__sincospif_stret"; + + assert(T.getArch() != Triple::x86 && "x86 messy and unsupported for now"); + // x86_64 can't use {float, float} since that would be returned in both + // xmm0 and xmm1, which isn't what a real struct would do. + ResTy = T.getArch() == Triple::x86_64 + ? static_cast<Type *>(VectorType::get(ArgTy, 2)) + : static_cast<Type *>(StructType::get(ArgTy, ArgTy, nullptr)); + } else { + Name = "__sincospi_stret"; + ResTy = StructType::get(ArgTy, ArgTy, nullptr); + } + + Module *M = OrigCallee->getParent(); + Value *Callee = M->getOrInsertFunction(Name, OrigCallee->getAttributes(), + ResTy, ArgTy, nullptr); + + if (Instruction *ArgInst = dyn_cast<Instruction>(Arg)) { + // If the argument is an instruction, it must dominate all uses so put our + // sincos call there. + B.SetInsertPoint(ArgInst->getParent(), ++ArgInst->getIterator()); + } else { + // Otherwise (e.g. for a constant) the beginning of the function is as + // good a place as any. + BasicBlock &EntryBB = B.GetInsertBlock()->getParent()->getEntryBlock(); + B.SetInsertPoint(&EntryBB, EntryBB.begin()); + } + + SinCos = B.CreateCall(Callee, Arg, "sincospi"); + + if (SinCos->getType()->isStructTy()) { + Sin = B.CreateExtractValue(SinCos, 0, "sinpi"); + Cos = B.CreateExtractValue(SinCos, 1, "cospi"); + } else { + Sin = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 0), + "sinpi"); + Cos = B.CreateExtractElement(SinCos, ConstantInt::get(B.getInt32Ty(), 1), + "cospi"); + } +} + +//===----------------------------------------------------------------------===// +// Integer Library Call Optimizations +//===----------------------------------------------------------------------===// + +static bool checkIntUnaryReturnAndParam(Function *Callee) { + FunctionType *FT = Callee->getFunctionType(); + return FT->getNumParams() == 1 && FT->getReturnType()->isIntegerTy(32) && + FT->getParamType(0)->isIntegerTy(); +} + +Value *LibCallSimplifier::optimizeFFS(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + if (!checkIntUnaryReturnAndParam(Callee)) + return nullptr; + Value *Op = CI->getArgOperand(0); + + // Constant fold. + if (ConstantInt *CI = dyn_cast<ConstantInt>(Op)) { + if (CI->isZero()) // ffs(0) -> 0. + return B.getInt32(0); + // ffs(c) -> cttz(c)+1 + return B.getInt32(CI->getValue().countTrailingZeros() + 1); + } + + // ffs(x) -> x != 0 ? (i32)llvm.cttz(x)+1 : 0 + Type *ArgType = Op->getType(); + Value *F = + Intrinsic::getDeclaration(Callee->getParent(), Intrinsic::cttz, ArgType); + Value *V = B.CreateCall(F, {Op, B.getTrue()}, "cttz"); + V = B.CreateAdd(V, ConstantInt::get(V->getType(), 1)); + V = B.CreateIntCast(V, B.getInt32Ty(), false); + + Value *Cond = B.CreateICmpNE(Op, Constant::getNullValue(ArgType)); + return B.CreateSelect(Cond, V, B.getInt32(0)); +} + +Value *LibCallSimplifier::optimizeAbs(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + FunctionType *FT = Callee->getFunctionType(); + // We require integer(integer) where the types agree. + if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() || + FT->getParamType(0) != FT->getReturnType()) + return nullptr; + + // abs(x) -> x >s -1 ? x : -x + Value *Op = CI->getArgOperand(0); + Value *Pos = + B.CreateICmpSGT(Op, Constant::getAllOnesValue(Op->getType()), "ispos"); + Value *Neg = B.CreateNeg(Op, "neg"); + return B.CreateSelect(Pos, Op, Neg); +} + +Value *LibCallSimplifier::optimizeIsDigit(CallInst *CI, IRBuilder<> &B) { + if (!checkIntUnaryReturnAndParam(CI->getCalledFunction())) + return nullptr; + + // isdigit(c) -> (c-'0') <u 10 + Value *Op = CI->getArgOperand(0); + Op = B.CreateSub(Op, B.getInt32('0'), "isdigittmp"); + Op = B.CreateICmpULT(Op, B.getInt32(10), "isdigit"); + return B.CreateZExt(Op, CI->getType()); +} + +Value *LibCallSimplifier::optimizeIsAscii(CallInst *CI, IRBuilder<> &B) { + if (!checkIntUnaryReturnAndParam(CI->getCalledFunction())) + return nullptr; + + // isascii(c) -> c <u 128 + Value *Op = CI->getArgOperand(0); + Op = B.CreateICmpULT(Op, B.getInt32(128), "isascii"); + return B.CreateZExt(Op, CI->getType()); +} + +Value *LibCallSimplifier::optimizeToAscii(CallInst *CI, IRBuilder<> &B) { + if (!checkIntUnaryReturnAndParam(CI->getCalledFunction())) + return nullptr; + + // toascii(c) -> c & 0x7f + return B.CreateAnd(CI->getArgOperand(0), + ConstantInt::get(CI->getType(), 0x7F)); +} + +//===----------------------------------------------------------------------===// +// Formatting and IO Library Call Optimizations +//===----------------------------------------------------------------------===// + +static bool isReportingError(Function *Callee, CallInst *CI, int StreamArg); + +Value *LibCallSimplifier::optimizeErrorReporting(CallInst *CI, IRBuilder<> &B, + int StreamArg) { + // Error reporting calls should be cold, mark them as such. + // This applies even to non-builtin calls: it is only a hint and applies to + // functions that the frontend might not understand as builtins. + + // This heuristic was suggested in: + // Improving Static Branch Prediction in a Compiler + // Brian L. Deitrich, Ben-Chung Cheng, Wen-mei W. Hwu + // Proceedings of PACT'98, Oct. 1998, IEEE + Function *Callee = CI->getCalledFunction(); + + if (!CI->hasFnAttr(Attribute::Cold) && + isReportingError(Callee, CI, StreamArg)) { + CI->addAttribute(AttributeSet::FunctionIndex, Attribute::Cold); + } + + return nullptr; +} + +static bool isReportingError(Function *Callee, CallInst *CI, int StreamArg) { + if (!ColdErrorCalls || !Callee || !Callee->isDeclaration()) + return false; + + if (StreamArg < 0) + return true; + + // These functions might be considered cold, but only if their stream + // argument is stderr. + + if (StreamArg >= (int)CI->getNumArgOperands()) + return false; + LoadInst *LI = dyn_cast<LoadInst>(CI->getArgOperand(StreamArg)); + if (!LI) + return false; + GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getPointerOperand()); + if (!GV || !GV->isDeclaration()) + return false; + return GV->getName() == "stderr"; +} + +Value *LibCallSimplifier::optimizePrintFString(CallInst *CI, IRBuilder<> &B) { + // Check for a fixed format string. + StringRef FormatStr; + if (!getConstantStringInfo(CI->getArgOperand(0), FormatStr)) + return nullptr; + + // Empty format string -> noop. + if (FormatStr.empty()) // Tolerate printf's declared void. + return CI->use_empty() ? (Value *)CI : ConstantInt::get(CI->getType(), 0); + + // Do not do any of the following transformations if the printf return value + // is used, in general the printf return value is not compatible with either + // putchar() or puts(). + if (!CI->use_empty()) + return nullptr; + + // printf("x") -> putchar('x'), even for '%'. + if (FormatStr.size() == 1) { + Value *Res = EmitPutChar(B.getInt32(FormatStr[0]), B, TLI); + if (CI->use_empty() || !Res) + return Res; + return B.CreateIntCast(Res, CI->getType(), true); + } + + // printf("foo\n") --> puts("foo") + if (FormatStr[FormatStr.size() - 1] == '\n' && + FormatStr.find('%') == StringRef::npos) { // No format characters. + // Create a string literal with no \n on it. We expect the constant merge + // pass to be run after this pass, to merge duplicate strings. + FormatStr = FormatStr.drop_back(); + Value *GV = B.CreateGlobalString(FormatStr, "str"); + Value *NewCI = EmitPutS(GV, B, TLI); + return (CI->use_empty() || !NewCI) + ? NewCI + : ConstantInt::get(CI->getType(), FormatStr.size() + 1); + } + + // Optimize specific format strings. + // printf("%c", chr) --> putchar(chr) + if (FormatStr == "%c" && CI->getNumArgOperands() > 1 && + CI->getArgOperand(1)->getType()->isIntegerTy()) { + Value *Res = EmitPutChar(CI->getArgOperand(1), B, TLI); + + if (CI->use_empty() || !Res) + return Res; + return B.CreateIntCast(Res, CI->getType(), true); + } + + // printf("%s\n", str) --> puts(str) + if (FormatStr == "%s\n" && CI->getNumArgOperands() > 1 && + CI->getArgOperand(1)->getType()->isPointerTy()) { + return EmitPutS(CI->getArgOperand(1), B, TLI); + } + return nullptr; +} + +Value *LibCallSimplifier::optimizePrintF(CallInst *CI, IRBuilder<> &B) { + + Function *Callee = CI->getCalledFunction(); + // Require one fixed pointer argument and an integer/void result. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() < 1 || !FT->getParamType(0)->isPointerTy() || + !(FT->getReturnType()->isIntegerTy() || FT->getReturnType()->isVoidTy())) + return nullptr; + + if (Value *V = optimizePrintFString(CI, B)) { + return V; + } + + // printf(format, ...) -> iprintf(format, ...) if no floating point + // arguments. + if (TLI->has(LibFunc::iprintf) && !callHasFloatingPointArgument(CI)) { + Module *M = B.GetInsertBlock()->getParent()->getParent(); + Constant *IPrintFFn = + M->getOrInsertFunction("iprintf", FT, Callee->getAttributes()); + CallInst *New = cast<CallInst>(CI->clone()); + New->setCalledFunction(IPrintFFn); + B.Insert(New); + return New; + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeSPrintFString(CallInst *CI, IRBuilder<> &B) { + // Check for a fixed format string. + StringRef FormatStr; + if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr)) + return nullptr; + + // If we just have a format string (nothing else crazy) transform it. + if (CI->getNumArgOperands() == 2) { + // Make sure there's no % in the constant array. We could try to handle + // %% -> % in the future if we cared. + for (unsigned i = 0, e = FormatStr.size(); i != e; ++i) + if (FormatStr[i] == '%') + return nullptr; // we found a format specifier, bail out. + + // sprintf(str, fmt) -> llvm.memcpy(str, fmt, strlen(fmt)+1, 1) + B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1), + ConstantInt::get(DL.getIntPtrType(CI->getContext()), + FormatStr.size() + 1), + 1); // Copy the null byte. + return ConstantInt::get(CI->getType(), FormatStr.size()); + } + + // The remaining optimizations require the format string to be "%s" or "%c" + // and have an extra operand. + if (FormatStr.size() != 2 || FormatStr[0] != '%' || + CI->getNumArgOperands() < 3) + return nullptr; + + // Decode the second character of the format string. + if (FormatStr[1] == 'c') { + // sprintf(dst, "%c", chr) --> *(i8*)dst = chr; *((i8*)dst+1) = 0 + if (!CI->getArgOperand(2)->getType()->isIntegerTy()) + return nullptr; + Value *V = B.CreateTrunc(CI->getArgOperand(2), B.getInt8Ty(), "char"); + Value *Ptr = CastToCStr(CI->getArgOperand(0), B); + B.CreateStore(V, Ptr); + Ptr = B.CreateGEP(B.getInt8Ty(), Ptr, B.getInt32(1), "nul"); + B.CreateStore(B.getInt8(0), Ptr); + + return ConstantInt::get(CI->getType(), 1); + } + + if (FormatStr[1] == 's') { + // sprintf(dest, "%s", str) -> llvm.memcpy(dest, str, strlen(str)+1, 1) + if (!CI->getArgOperand(2)->getType()->isPointerTy()) + return nullptr; + + Value *Len = EmitStrLen(CI->getArgOperand(2), B, DL, TLI); + if (!Len) + return nullptr; + Value *IncLen = + B.CreateAdd(Len, ConstantInt::get(Len->getType(), 1), "leninc"); + B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(2), IncLen, 1); + + // The sprintf result is the unincremented number of bytes in the string. + return B.CreateIntCast(Len, CI->getType(), false); + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeSPrintF(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Require two fixed pointer arguments and an integer result. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + if (Value *V = optimizeSPrintFString(CI, B)) { + return V; + } + + // sprintf(str, format, ...) -> siprintf(str, format, ...) if no floating + // point arguments. + if (TLI->has(LibFunc::siprintf) && !callHasFloatingPointArgument(CI)) { + Module *M = B.GetInsertBlock()->getParent()->getParent(); + Constant *SIPrintFFn = + M->getOrInsertFunction("siprintf", FT, Callee->getAttributes()); + CallInst *New = cast<CallInst>(CI->clone()); + New->setCalledFunction(SIPrintFFn); + B.Insert(New); + return New; + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeFPrintFString(CallInst *CI, IRBuilder<> &B) { + optimizeErrorReporting(CI, B, 0); + + // All the optimizations depend on the format string. + StringRef FormatStr; + if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr)) + return nullptr; + + // Do not do any of the following transformations if the fprintf return + // value is used, in general the fprintf return value is not compatible + // with fwrite(), fputc() or fputs(). + if (!CI->use_empty()) + return nullptr; + + // fprintf(F, "foo") --> fwrite("foo", 3, 1, F) + if (CI->getNumArgOperands() == 2) { + for (unsigned i = 0, e = FormatStr.size(); i != e; ++i) + if (FormatStr[i] == '%') // Could handle %% -> % if we cared. + return nullptr; // We found a format specifier. + + return EmitFWrite( + CI->getArgOperand(1), + ConstantInt::get(DL.getIntPtrType(CI->getContext()), FormatStr.size()), + CI->getArgOperand(0), B, DL, TLI); + } + + // The remaining optimizations require the format string to be "%s" or "%c" + // and have an extra operand. + if (FormatStr.size() != 2 || FormatStr[0] != '%' || + CI->getNumArgOperands() < 3) + return nullptr; + + // Decode the second character of the format string. + if (FormatStr[1] == 'c') { + // fprintf(F, "%c", chr) --> fputc(chr, F) + if (!CI->getArgOperand(2)->getType()->isIntegerTy()) + return nullptr; + return EmitFPutC(CI->getArgOperand(2), CI->getArgOperand(0), B, TLI); + } + + if (FormatStr[1] == 's') { + // fprintf(F, "%s", str) --> fputs(str, F) + if (!CI->getArgOperand(2)->getType()->isPointerTy()) + return nullptr; + return EmitFPutS(CI->getArgOperand(2), CI->getArgOperand(0), B, TLI); + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeFPrintF(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Require two fixed paramters as pointers and integer result. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + if (Value *V = optimizeFPrintFString(CI, B)) { + return V; + } + + // fprintf(stream, format, ...) -> fiprintf(stream, format, ...) if no + // floating point arguments. + if (TLI->has(LibFunc::fiprintf) && !callHasFloatingPointArgument(CI)) { + Module *M = B.GetInsertBlock()->getParent()->getParent(); + Constant *FIPrintFFn = + M->getOrInsertFunction("fiprintf", FT, Callee->getAttributes()); + CallInst *New = cast<CallInst>(CI->clone()); + New->setCalledFunction(FIPrintFFn); + B.Insert(New); + return New; + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeFWrite(CallInst *CI, IRBuilder<> &B) { + optimizeErrorReporting(CI, B, 3); + + Function *Callee = CI->getCalledFunction(); + // Require a pointer, an integer, an integer, a pointer, returning integer. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isIntegerTy() || + !FT->getParamType(2)->isIntegerTy() || + !FT->getParamType(3)->isPointerTy() || + !FT->getReturnType()->isIntegerTy()) + return nullptr; + + // Get the element size and count. + ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1)); + ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2)); + if (!SizeC || !CountC) + return nullptr; + uint64_t Bytes = SizeC->getZExtValue() * CountC->getZExtValue(); + + // If this is writing zero records, remove the call (it's a noop). + if (Bytes == 0) + return ConstantInt::get(CI->getType(), 0); + + // If this is writing one byte, turn it into fputc. + // This optimisation is only valid, if the return value is unused. + if (Bytes == 1 && CI->use_empty()) { // fwrite(S,1,1,F) -> fputc(S[0],F) + Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char"); + Value *NewCI = EmitFPutC(Char, CI->getArgOperand(3), B, TLI); + return NewCI ? ConstantInt::get(CI->getType(), 1) : nullptr; + } + + return nullptr; +} + +Value *LibCallSimplifier::optimizeFPuts(CallInst *CI, IRBuilder<> &B) { + optimizeErrorReporting(CI, B, 1); + + Function *Callee = CI->getCalledFunction(); + + // Require two pointers. Also, we can't optimize if return value is used. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() != 2 || !FT->getParamType(0)->isPointerTy() || + !FT->getParamType(1)->isPointerTy() || !CI->use_empty()) + return nullptr; + + // fputs(s,F) --> fwrite(s,1,strlen(s),F) + uint64_t Len = GetStringLength(CI->getArgOperand(0)); + if (!Len) + return nullptr; + + // Known to have no uses (see above). + return EmitFWrite( + CI->getArgOperand(0), + ConstantInt::get(DL.getIntPtrType(CI->getContext()), Len - 1), + CI->getArgOperand(1), B, DL, TLI); +} + +Value *LibCallSimplifier::optimizePuts(CallInst *CI, IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + // Require one fixed pointer argument and an integer/void result. + FunctionType *FT = Callee->getFunctionType(); + if (FT->getNumParams() < 1 || !FT->getParamType(0)->isPointerTy() || + !(FT->getReturnType()->isIntegerTy() || FT->getReturnType()->isVoidTy())) + return nullptr; + + // Check for a constant string. + StringRef Str; + if (!getConstantStringInfo(CI->getArgOperand(0), Str)) + return nullptr; + + if (Str.empty() && CI->use_empty()) { + // puts("") -> putchar('\n') + Value *Res = EmitPutChar(B.getInt32('\n'), B, TLI); + if (CI->use_empty() || !Res) + return Res; + return B.CreateIntCast(Res, CI->getType(), true); + } + + return nullptr; +} + +bool LibCallSimplifier::hasFloatVersion(StringRef FuncName) { + LibFunc::Func Func; + SmallString<20> FloatFuncName = FuncName; + FloatFuncName += 'f'; + if (TLI->getLibFunc(FloatFuncName, Func)) + return TLI->has(Func); + return false; +} + +Value *LibCallSimplifier::optimizeStringMemoryLibCall(CallInst *CI, + IRBuilder<> &Builder) { + LibFunc::Func Func; + Function *Callee = CI->getCalledFunction(); + StringRef FuncName = Callee->getName(); + + // Check for string/memory library functions. + if (TLI->getLibFunc(FuncName, Func) && TLI->has(Func)) { + // Make sure we never change the calling convention. + assert((ignoreCallingConv(Func) || + CI->getCallingConv() == llvm::CallingConv::C) && + "Optimizing string/memory libcall would change the calling convention"); + switch (Func) { + case LibFunc::strcat: + return optimizeStrCat(CI, Builder); + case LibFunc::strncat: + return optimizeStrNCat(CI, Builder); + case LibFunc::strchr: + return optimizeStrChr(CI, Builder); + case LibFunc::strrchr: + return optimizeStrRChr(CI, Builder); + case LibFunc::strcmp: + return optimizeStrCmp(CI, Builder); + case LibFunc::strncmp: + return optimizeStrNCmp(CI, Builder); + case LibFunc::strcpy: + return optimizeStrCpy(CI, Builder); + case LibFunc::stpcpy: + return optimizeStpCpy(CI, Builder); + case LibFunc::strncpy: + return optimizeStrNCpy(CI, Builder); + case LibFunc::strlen: + return optimizeStrLen(CI, Builder); + case LibFunc::strpbrk: + return optimizeStrPBrk(CI, Builder); + case LibFunc::strtol: + case LibFunc::strtod: + case LibFunc::strtof: + case LibFunc::strtoul: + case LibFunc::strtoll: + case LibFunc::strtold: + case LibFunc::strtoull: + return optimizeStrTo(CI, Builder); + case LibFunc::strspn: + return optimizeStrSpn(CI, Builder); + case LibFunc::strcspn: + return optimizeStrCSpn(CI, Builder); + case LibFunc::strstr: + return optimizeStrStr(CI, Builder); + case LibFunc::memchr: + return optimizeMemChr(CI, Builder); + case LibFunc::memcmp: + return optimizeMemCmp(CI, Builder); + case LibFunc::memcpy: + return optimizeMemCpy(CI, Builder); + case LibFunc::memmove: + return optimizeMemMove(CI, Builder); + case LibFunc::memset: + return optimizeMemSet(CI, Builder); + default: + break; + } + } + return nullptr; +} + +Value *LibCallSimplifier::optimizeCall(CallInst *CI) { + if (CI->isNoBuiltin()) + return nullptr; + + LibFunc::Func Func; + Function *Callee = CI->getCalledFunction(); + StringRef FuncName = Callee->getName(); + + SmallVector<OperandBundleDef, 2> OpBundles; + CI->getOperandBundlesAsDefs(OpBundles); + IRBuilder<> Builder(CI, /*FPMathTag=*/nullptr, OpBundles); + bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C; + + // Command-line parameter overrides function attribute. + if (EnableUnsafeFPShrink.getNumOccurrences() > 0) + UnsafeFPShrink = EnableUnsafeFPShrink; + else if (canUseUnsafeFPMath(Callee)) + UnsafeFPShrink = true; + + // First, check for intrinsics. + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) { + if (!isCallingConvC) + return nullptr; + switch (II->getIntrinsicID()) { + case Intrinsic::pow: + return optimizePow(CI, Builder); + case Intrinsic::exp2: + return optimizeExp2(CI, Builder); + case Intrinsic::fabs: + return optimizeFabs(CI, Builder); + case Intrinsic::log: + return optimizeLog(CI, Builder); + case Intrinsic::sqrt: + return optimizeSqrt(CI, Builder); + default: + return nullptr; + } + } + + // Also try to simplify calls to fortified library functions. + if (Value *SimplifiedFortifiedCI = FortifiedSimplifier.optimizeCall(CI)) { + // Try to further simplify the result. + CallInst *SimplifiedCI = dyn_cast<CallInst>(SimplifiedFortifiedCI); + if (SimplifiedCI && SimplifiedCI->getCalledFunction()) { + // Use an IR Builder from SimplifiedCI if available instead of CI + // to guarantee we reach all uses we might replace later on. + IRBuilder<> TmpBuilder(SimplifiedCI); + if (Value *V = optimizeStringMemoryLibCall(SimplifiedCI, TmpBuilder)) { + // If we were able to further simplify, remove the now redundant call. + SimplifiedCI->replaceAllUsesWith(V); + SimplifiedCI->eraseFromParent(); + return V; + } + } + return SimplifiedFortifiedCI; + } + + // Then check for known library functions. + if (TLI->getLibFunc(FuncName, Func) && TLI->has(Func)) { + // We never change the calling convention. + if (!ignoreCallingConv(Func) && !isCallingConvC) + return nullptr; + if (Value *V = optimizeStringMemoryLibCall(CI, Builder)) + return V; + switch (Func) { + case LibFunc::cosf: + case LibFunc::cos: + case LibFunc::cosl: + return optimizeCos(CI, Builder); + case LibFunc::sinpif: + case LibFunc::sinpi: + case LibFunc::cospif: + case LibFunc::cospi: + return optimizeSinCosPi(CI, Builder); + case LibFunc::powf: + case LibFunc::pow: + case LibFunc::powl: + return optimizePow(CI, Builder); + case LibFunc::exp2l: + case LibFunc::exp2: + case LibFunc::exp2f: + return optimizeExp2(CI, Builder); + case LibFunc::fabsf: + case LibFunc::fabs: + case LibFunc::fabsl: + return optimizeFabs(CI, Builder); + case LibFunc::sqrtf: + case LibFunc::sqrt: + case LibFunc::sqrtl: + return optimizeSqrt(CI, Builder); + case LibFunc::ffs: + case LibFunc::ffsl: + case LibFunc::ffsll: + return optimizeFFS(CI, Builder); + case LibFunc::abs: + case LibFunc::labs: + case LibFunc::llabs: + return optimizeAbs(CI, Builder); + case LibFunc::isdigit: + return optimizeIsDigit(CI, Builder); + case LibFunc::isascii: + return optimizeIsAscii(CI, Builder); + case LibFunc::toascii: + return optimizeToAscii(CI, Builder); + case LibFunc::printf: + return optimizePrintF(CI, Builder); + case LibFunc::sprintf: + return optimizeSPrintF(CI, Builder); + case LibFunc::fprintf: + return optimizeFPrintF(CI, Builder); + case LibFunc::fwrite: + return optimizeFWrite(CI, Builder); + case LibFunc::fputs: + return optimizeFPuts(CI, Builder); + case LibFunc::log: + case LibFunc::log10: + case LibFunc::log1p: + case LibFunc::log2: + case LibFunc::logb: + return optimizeLog(CI, Builder); + case LibFunc::puts: + return optimizePuts(CI, Builder); + case LibFunc::tan: + case LibFunc::tanf: + case LibFunc::tanl: + return optimizeTan(CI, Builder); + case LibFunc::perror: + return optimizeErrorReporting(CI, Builder); + case LibFunc::vfprintf: + case LibFunc::fiprintf: + return optimizeErrorReporting(CI, Builder, 0); + case LibFunc::fputc: + return optimizeErrorReporting(CI, Builder, 1); + case LibFunc::ceil: + case LibFunc::floor: + case LibFunc::rint: + case LibFunc::round: + case LibFunc::nearbyint: + case LibFunc::trunc: + if (hasFloatVersion(FuncName)) + return optimizeUnaryDoubleFP(CI, Builder, false); + return nullptr; + case LibFunc::acos: + case LibFunc::acosh: + case LibFunc::asin: + case LibFunc::asinh: + case LibFunc::atan: + case LibFunc::atanh: + case LibFunc::cbrt: + case LibFunc::cosh: + case LibFunc::exp: + case LibFunc::exp10: + case LibFunc::expm1: + case LibFunc::sin: + case LibFunc::sinh: + case LibFunc::tanh: + if (UnsafeFPShrink && hasFloatVersion(FuncName)) + return optimizeUnaryDoubleFP(CI, Builder, true); + return nullptr; + case LibFunc::copysign: + if (hasFloatVersion(FuncName)) + return optimizeBinaryDoubleFP(CI, Builder); + return nullptr; + case LibFunc::fminf: + case LibFunc::fmin: + case LibFunc::fminl: + case LibFunc::fmaxf: + case LibFunc::fmax: + case LibFunc::fmaxl: + return optimizeFMinFMax(CI, Builder); + default: + return nullptr; + } + } + return nullptr; +} + +LibCallSimplifier::LibCallSimplifier( + const DataLayout &DL, const TargetLibraryInfo *TLI, + function_ref<void(Instruction *, Value *)> Replacer) + : FortifiedSimplifier(TLI), DL(DL), TLI(TLI), UnsafeFPShrink(false), + Replacer(Replacer) {} + +void LibCallSimplifier::replaceAllUsesWith(Instruction *I, Value *With) { + // Indirect through the replacer used in this instance. + Replacer(I, With); +} + +// TODO: +// Additional cases that we need to add to this file: +// +// cbrt: +// * cbrt(expN(X)) -> expN(x/3) +// * cbrt(sqrt(x)) -> pow(x,1/6) +// * cbrt(cbrt(x)) -> pow(x,1/9) +// +// exp, expf, expl: +// * exp(log(x)) -> x +// +// log, logf, logl: +// * log(exp(x)) -> x +// * log(exp(y)) -> y*log(e) +// * log(exp10(y)) -> y*log(10) +// * log(sqrt(x)) -> 0.5*log(x) +// +// lround, lroundf, lroundl: +// * lround(cnst) -> cnst' +// +// pow, powf, powl: +// * pow(sqrt(x),y) -> pow(x,y*0.5) +// * pow(pow(x,y),z)-> pow(x,y*z) +// +// round, roundf, roundl: +// * round(cnst) -> cnst' +// +// signbit: +// * signbit(cnst) -> cnst' +// * signbit(nncst) -> 0 (if pstv is a non-negative constant) +// +// sqrt, sqrtf, sqrtl: +// * sqrt(expN(x)) -> expN(x*0.5) +// * sqrt(Nroot(x)) -> pow(x,1/(2*N)) +// * sqrt(pow(x,y)) -> pow(|x|,y*0.5) +// +// trunc, truncf, truncl: +// * trunc(cnst) -> cnst' +// +// + +//===----------------------------------------------------------------------===// +// Fortified Library Call Optimizations +//===----------------------------------------------------------------------===// + +bool FortifiedLibCallSimplifier::isFortifiedCallFoldable(CallInst *CI, + unsigned ObjSizeOp, + unsigned SizeOp, + bool isString) { + if (CI->getArgOperand(ObjSizeOp) == CI->getArgOperand(SizeOp)) + return true; + if (ConstantInt *ObjSizeCI = + dyn_cast<ConstantInt>(CI->getArgOperand(ObjSizeOp))) { + if (ObjSizeCI->isAllOnesValue()) + return true; + // If the object size wasn't -1 (unknown), bail out if we were asked to. + if (OnlyLowerUnknownSize) + return false; + if (isString) { + uint64_t Len = GetStringLength(CI->getArgOperand(SizeOp)); + // If the length is 0 we don't know how long it is and so we can't + // remove the check. + if (Len == 0) + return false; + return ObjSizeCI->getZExtValue() >= Len; + } + if (ConstantInt *SizeCI = dyn_cast<ConstantInt>(CI->getArgOperand(SizeOp))) + return ObjSizeCI->getZExtValue() >= SizeCI->getZExtValue(); + } + return false; +} + +Value *FortifiedLibCallSimplifier::optimizeMemCpyChk(CallInst *CI, + IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memcpy_chk)) + return nullptr; + + if (isFortifiedCallFoldable(CI, 3, 2, false)) { + B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1), + CI->getArgOperand(2), 1); + return CI->getArgOperand(0); + } + return nullptr; +} + +Value *FortifiedLibCallSimplifier::optimizeMemMoveChk(CallInst *CI, + IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memmove_chk)) + return nullptr; + + if (isFortifiedCallFoldable(CI, 3, 2, false)) { + B.CreateMemMove(CI->getArgOperand(0), CI->getArgOperand(1), + CI->getArgOperand(2), 1); + return CI->getArgOperand(0); + } + return nullptr; +} + +Value *FortifiedLibCallSimplifier::optimizeMemSetChk(CallInst *CI, + IRBuilder<> &B) { + Function *Callee = CI->getCalledFunction(); + + if (!checkStringCopyLibFuncSignature(Callee, LibFunc::memset_chk)) + return nullptr; + + if (isFortifiedCallFoldable(CI, 3, 2, false)) { + Value *Val = B.CreateIntCast(CI->getArgOperand(1), B.getInt8Ty(), false); + B.CreateMemSet(CI->getArgOperand(0), Val, CI->getArgOperand(2), 1); + return CI->getArgOperand(0); + } + return nullptr; +} + +Value *FortifiedLibCallSimplifier::optimizeStrpCpyChk(CallInst *CI, + IRBuilder<> &B, + LibFunc::Func Func) { + Function *Callee = CI->getCalledFunction(); + StringRef Name = Callee->getName(); + const DataLayout &DL = CI->getModule()->getDataLayout(); + + if (!checkStringCopyLibFuncSignature(Callee, Func)) + return nullptr; + + Value *Dst = CI->getArgOperand(0), *Src = CI->getArgOperand(1), + *ObjSize = CI->getArgOperand(2); + + // __stpcpy_chk(x,x,...) -> x+strlen(x) + if (Func == LibFunc::stpcpy_chk && !OnlyLowerUnknownSize && Dst == Src) { + Value *StrLen = EmitStrLen(Src, B, DL, TLI); + return StrLen ? B.CreateInBoundsGEP(B.getInt8Ty(), Dst, StrLen) : nullptr; + } + + // If a) we don't have any length information, or b) we know this will + // fit then just lower to a plain st[rp]cpy. Otherwise we'll keep our + // st[rp]cpy_chk call which may fail at runtime if the size is too long. + // TODO: It might be nice to get a maximum length out of the possible + // string lengths for varying. + if (isFortifiedCallFoldable(CI, 2, 1, true)) + return EmitStrCpy(Dst, Src, B, TLI, Name.substr(2, 6)); + + if (OnlyLowerUnknownSize) + return nullptr; + + // Maybe we can stil fold __st[rp]cpy_chk to __memcpy_chk. + uint64_t Len = GetStringLength(Src); + if (Len == 0) + return nullptr; + + Type *SizeTTy = DL.getIntPtrType(CI->getContext()); + Value *LenV = ConstantInt::get(SizeTTy, Len); + Value *Ret = EmitMemCpyChk(Dst, Src, LenV, ObjSize, B, DL, TLI); + // If the function was an __stpcpy_chk, and we were able to fold it into + // a __memcpy_chk, we still need to return the correct end pointer. + if (Ret && Func == LibFunc::stpcpy_chk) + return B.CreateGEP(B.getInt8Ty(), Dst, ConstantInt::get(SizeTTy, Len - 1)); + return Ret; +} + +Value *FortifiedLibCallSimplifier::optimizeStrpNCpyChk(CallInst *CI, + IRBuilder<> &B, + LibFunc::Func Func) { + Function *Callee = CI->getCalledFunction(); + StringRef Name = Callee->getName(); + + if (!checkStringCopyLibFuncSignature(Callee, Func)) + return nullptr; + if (isFortifiedCallFoldable(CI, 3, 2, false)) { + Value *Ret = EmitStrNCpy(CI->getArgOperand(0), CI->getArgOperand(1), + CI->getArgOperand(2), B, TLI, Name.substr(2, 7)); + return Ret; + } + return nullptr; +} + +Value *FortifiedLibCallSimplifier::optimizeCall(CallInst *CI) { + // FIXME: We shouldn't be changing "nobuiltin" or TLI unavailable calls here. + // Some clang users checked for _chk libcall availability using: + // __has_builtin(__builtin___memcpy_chk) + // When compiling with -fno-builtin, this is always true. + // When passing -ffreestanding/-mkernel, which both imply -fno-builtin, we + // end up with fortified libcalls, which isn't acceptable in a freestanding + // environment which only provides their non-fortified counterparts. + // + // Until we change clang and/or teach external users to check for availability + // differently, disregard the "nobuiltin" attribute and TLI::has. + // + // PR23093. + + LibFunc::Func Func; + Function *Callee = CI->getCalledFunction(); + StringRef FuncName = Callee->getName(); + + SmallVector<OperandBundleDef, 2> OpBundles; + CI->getOperandBundlesAsDefs(OpBundles); + IRBuilder<> Builder(CI, /*FPMathTag=*/nullptr, OpBundles); + bool isCallingConvC = CI->getCallingConv() == llvm::CallingConv::C; + + // First, check that this is a known library functions. + if (!TLI->getLibFunc(FuncName, Func)) + return nullptr; + + // We never change the calling convention. + if (!ignoreCallingConv(Func) && !isCallingConvC) + return nullptr; + + switch (Func) { + case LibFunc::memcpy_chk: + return optimizeMemCpyChk(CI, Builder); + case LibFunc::memmove_chk: + return optimizeMemMoveChk(CI, Builder); + case LibFunc::memset_chk: + return optimizeMemSetChk(CI, Builder); + case LibFunc::stpcpy_chk: + case LibFunc::strcpy_chk: + return optimizeStrpCpyChk(CI, Builder, Func); + case LibFunc::stpncpy_chk: + case LibFunc::strncpy_chk: + return optimizeStrpNCpyChk(CI, Builder, Func); + default: + break; + } + return nullptr; +} + +FortifiedLibCallSimplifier::FortifiedLibCallSimplifier( + const TargetLibraryInfo *TLI, bool OnlyLowerUnknownSize) + : TLI(TLI), OnlyLowerUnknownSize(OnlyLowerUnknownSize) {} |
